Recent years has seen advances in the development of communication systems that adopt femto-cell base stations that seek to achieve an improvement in quality of communication areas.
A femto-cell base station is a compact wireless base station that covers a limited communication area having a radius in the order of several tens of meters. A femto-cell base station is installed in a room such as a residence or office to cover an indoor communication area. The use of a femto-cell base station enables improvement of communication quality of communication areas that cannot be covered by existing macro-cell base stations. In addition, communication areas can be covered without adding costs for setting up the infrastructure of macro-cell base stations.
Existing 3G networks (communication systems) have been established between users and communication common carriers. “Existing 3G network” refers to a communication network that carries out communication via existing macro-cell base stations. As a result, constructing a new communication system by improving the existing 3G network for the purpose of introducing femto-cell base stations both results in high costs and places various burdens on the communication common carrier and users that use the existing 3G network.
As a result, rather than improve an existing 3G network, a new communication system must be built that can accept femto-cell base stations.
Literature exists that discloses technology for accessing IMS by way of WLAN/WWAN that takes into consideration related existing standard specifications (See Patent Document 1).
Literature exists that discloses certification technology for WLAN.    Patent Document 1: JP-A-2006-525762    Non-Patent Document 1: 3GPP TS 33.234 V8.0.0 (2007-12)